Let's roll up our sleeves and solve this. We have 657 and we're going to multiply it by 19, essentially adding 657 to itself 19 times.
Step 1: 0 + 657 = 657
Step 2: 657 + 657 = 1314
Step 3: 1314 + 657 = 1971
Step 4: 1971 + 657 = 2628
Step 5: 2628 + 657 = 3285
Step 6: 3285 + 657 = 3942
Step 7: 3942 + 657 = 4599
Step 8: 4599 + 657 = 5256
Step 9: 5256 + 657 = 5913
Step 10: 5913 + 657 = 6570
Step 11: 6570 + 657 = 7227
Step 12: 7227 + 657 = 7884
Step 13: 7884 + 657 = 8541
Step 14: 8541 + 657 = 9198
Step 15: 9198 + 657 = 9855
Step 16: 9855 + 657 = 10512
Step 17: 10512 + 657 = 11169
Step 18: 11169 + 657 = 11826
Step 19: 11826 + 657 = 12483

So, 657*19 = 12483